Display device having a graphical user interface



The FIGURE is a front view of a display device having a graphical user interface.

The outermost broken-line perimeter illustrates the display screen of a display device and forms no part of the claimed design. The remaining broken lines illustrate portions of the graphical user interface and form no part of the claimed design. 

CLAIM What is claimed is the ornamental design for a display device having a graphical user interface, as shown and described. 